Dissociative ionization of the 
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 molecule induced by medium-energy singly charged projectiles

Kovács, Sándor; Herczku, Péter; Juhász, Zoltán; Sarkadi, L.; Gulyás, László; Sulik, B.

doi:10.1103/physreva.96.032704

Cited by 9 publications

(8 citation statements)

References 47 publications

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“…The presently obtained energy spectra of cations show a striking difference from those obtained in collisions involving projectiles of higher charge or higher energy [25][26][27][28][29], as shown in Fig. 8.…”

Section: Many-body Processes Versus Coulomb Explosion In Differentmentioning

confidence: 75%

Anion and cation emission from water molecules after collisions with 6.6-keV 16O+ ions

et al. 2019

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Anion and cation emission following water dissociation was studied for 6.6-keV 16 O + + H2O collisions. Absolute cross sections for the emission of all positively and negatively charged fragments, differential in both energy and observation angle, were measured. The fragments formed in hard, binary collisions appearing in peaks were distinguishable from those created in soft collisions with many-body dynamics that result in a broad energy spectrum. A striking feature is that anions and cations are emitted with similar energy and angular distributions, with a nearly constant ratio of about 1:100 for Hto H + . Model calculations were performed at different levels of complexity. Four-body scattering simulations reproduce the measured fragment distributions if adequate kinetic-energy release of the target is taken into account. Providing even further insight into the underlying processes, predictions of a thermodynamic model indicate that transfer ionization at small impact parameters is the dominant mechanism for H + creation. The present findings confirm our earlier observation that in molecular fragmentation induced by slow, singly charged ions, the charge states of the emitted hydrogen fragments follow a simple statistical distribution independent of the way they are formed.

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Section: Many-body Processes Versus Coulomb Explosion In Differentmentioning

confidence: 75%

Anion and cation emission from water molecules after collisions with 6.6-keV 16O+ ions

et al. 2019

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“…The account of the final states and the kinetic energies of the DI products is an important general problem dealing with the theoretical and experimental determinations of the appearance energies, in particular, at the inelastic collisions of fast ions with molecules, which lead to the formation of multiply charged molecular ions followed by their Coulombic decay. For example, it occurs in the processes of interaction of the H + , He + , and N + ions (with energies of 1 and 2 MeV) with water and ethane (C 2 H 6 ) molecules [77][78][79]. In the framework of this problem, the determination of the total released kinetic energy of fragments is an important component in the microscopic analysis of the dynamics of various reactions running in the course of the DI process.…”

Section: Basic Issuesmentioning

confidence: 99%

Inelastic Processes of Electron Interaction with Chalcogens in the Gaseous Phase (a Review)

et al. 2020

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Complex research of elementary pair collision processes occurring when low-energy (0–70 eV) electrons pass through chalcogen (S, Se, Te) vapor has been carried out in the evaporation temperature intervals of those elements (T = 320÷700 K for sulfur, 420÷490 K for selenium, and 400÷600 K for tellurium). The vapor compositions of indicated elements are studied using the mass spectroscopy method. The radiation spectra are analyzed in the wavelength interval from 200 to 600 nm with the help of optical spectroscopy. Using highly monoenergetic electron beams, the total (integral) formation cross-sections for positive and negative S, Se, and Te ions are measured. It is found that, under the experimental conditions, the main components of chalcogen vapor are molecules containing 2 to 8 atoms. At the energies of bombarding electrons below 10 eV, the emission spectra mainly consist of bands of diatomic molecules, and, at higher energies (E > 15 eV), there appear separate atomic and ionic lines. At E = 50 eV, the lines of singly charged ions are the most intense ones. It is shown that the most effective reaction channel is the interaction of electrons with diatomic molecules of indicated elements, whereas other processes are mainly associated with the decay of polyatomic molecules. The excitation and ionization thresholds for interaction products are found by analyzing the energy dependences of process characteristics. Specific features are also observed in the energy dependences of the excitation and ionization functions. Doubly charged ions of diatomic sulfur molecules, as well as selenium and tellurium atoms, are revealed for the first time. The appearance of triply charged ions of diatomic sulfur molecules is also detected. The main contribution to the total (integral) effective ionization cross-section of both positive and negative ions is proved to be made by the interaction processes of electrons with diatomic molecules S2, Se2, and Te2. Besides the experimental research, a detailed theoretical study is carried out. Calculations with a theoretical analysis of their results are performed for the structural characteristics of homoatomic sulfur, Sn, selenium, Sen, and tellurium, Ten, molecules with n = 2÷8; namely, interatomic distances, ionization potentials, electron affinity energies, and dissociation energies. The energy characteristics are applied to calculate the appearance energies for singly and doubly charged ionic fragments of those molecules at the dissociative ionization. The obtained results are carefully compared with the available experimental and theoretical data.

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“…The kinetic energy of fragments produced by several processes is also indicated. (1) Values from Kovács et al (2017). 2Value from Kimmel & Orlando (1995) for the electron-induced dissociation of D 2 O in the ice phase (we assume that for H 2 O H fragments would have the same velocity as the velocity of D fragments estimated by Kimmel & Orlando 1995).…”

Section: Desorption Processes Related To Molecularmentioning

confidence: 99%

“…GCRs can directly collide with icy grains and dissociate molecules. Kovács et al (2017) have measured the energy distribution of the fragments released by 1 MeV collisions of H + with water, yielding mainly neutral and singly positively charged O and OH fragments, as well as protons and electrons, with energy ranging from 1 to 12 eV (or 12,000-139,000 K) for the oxygen-bearing fragments and 2.5-12 eV (or 29,010-139,000 K) for the protons. The surface roughness does not impact the desorption rate of fragments produced by direct cosmic-ray impact and thus the composition of icy mantles, as the velocities of the produced fragments are much too high for recapture to occur (see Figures 5 and 6).…”

Section: Desorption Processes Related To Molecularmentioning

confidence: 99%

Effect of the Surface Roughness of Icy Grains on Molecular Oxygen Chemistry in Molecular Clouds

Maggiolo

Gibbons

Cessateur

et al. 2019

ApJ

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Molecular cloud and protosolar nebula chemistry involves a strong interaction between the gas phase and the surface of icy grains. The exchanges between the gas phase and the solid phase depend not only on the adsorption and desorption rates but also on the geometry of the surface of the grains. Indeed, for sufficient levels of surface roughness, atoms and molecules have a significant probability to collide with the grain icy mantle several times before being potentially captured. In consequence, their net sticking probability may differ from their sticking probability for a single collision with the grain surface. We estimate the effectiveness of the recapture on uneven surfaces for the various desorption processes at play in astrophysical environments. We show that surface roughness has a significant effect on the desorption rates. We focus in particular on the production of O 2 since unexpectedly large amounts of it, probably incorporated in the comet when it formed, have been detected in the coma of comet 67P by the Rosetta probe. Our results suggest that the higher escape probability of hydrogen compared to heavier species on rough surfaces can contribute to enhancing the production of O 2 in the icy mantles of grains while keeping its abundance low in the gas phase and may significantly decrease the desorption probability of molecules involved in the O 2 chemical network.

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Dissociative ionization of the H2O molecule induced by medium-energy singly charged projectiles

Cited by 9 publications

References 47 publications

Anion and cation emission from water molecules after collisions with 6.6-keV 16O+ ions

Anion and cation emission from water molecules after collisions with 6.6-keV 16O+ ions

Inelastic Processes of Electron Interaction with Chalcogens in the Gaseous Phase (a Review)

Effect of the Surface Roughness of Icy Grains on Molecular Oxygen Chemistry in Molecular Clouds

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